29 U.S. Code § 528 - Criminal contempt

No person shall be punished for any criminal contempt allegedly committed outside the immediate presence of the court in connection with any civil action prosecuted by the Secretary or any other person in any court of the United States under the provisions of this chapter unless the facts constituting such criminal contempt are established by the verdict of the jury in a proceeding in the district court of the United States, which jury shall be chosen and empaneled in the manner prescribed by the law governing trial juries in criminal prosecutions in the district courts of the United States.